Lifehacker have an article up on their website detailing the process of switching from the default fonts used by most websites and the computer system to the Vista fonts. This is easier done than one would think. A user who wants to enable those fonts in the Firefox web browser needs to have a working installation of Microsoft PowerPoint 2007, Microsoft Office 2007 or the free Microsoft PowerPoint Viewer 2007. This ensures that the Vista fonts are installed on the computer system. Vista users do not need to perform this operation since their operating system ships with those fonts.

The next step involves switching to ClearType if the computer is connected to an LCD monitor. This can be done with a powertoy from Microsoft.

It is then time to configure Firefox to use the Vista fonts instead of the default fonts after installation of the fonts and enabling ClearType. This is done in the Tools > Options > Content menu. A click on the advanced button under Fonts & Colors will display the following configuration menu. Just switch to the same fonts and settings that are shown in the following image:

It is important to uncheck the checkbox at the bottom to prevent pages from selecting the fonts. The result can be a better readability and is something worth to try.